<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>菜鸟教程(runoob.com)</title>
    <style>
        body {
            margin-left: 200px;
            background: #5d9ab2 url('http://static.runoob.com/images/mix/img_tree.png') no-repeat top left;
        }

        .container {
            text-align: center;
        }

        .center_div {
            border: 1px solid gray;
            margin-left: auto;
            margin-right: auto;
            width: 90%;
            background-color: #d0f0f6;
            text-align: left;
            padding: 8px;
        }
    </style>
</head>

<body>
    <div class="container">
        <div class="center_div">
            <h1>Hello World!</h1>
            <p>这个实例包含了一些高级的 CSS 方法，后面章节会介绍到。</p>
        </div>
    </div>
</body>

</html>